FR2882434A3 - INDUCTIVE PRESSURE SENSOR, ESPECIALLY FOR HOUSEHOLD APPLIANCES, BOILERS AND OTHER - Google Patents

Abstract

The sensor (1) comprises a rigid casing (2) having at least one inlet (5) for a pressure to be measured, in which is defined a chamber (12) in which is mounted in a sealed manner a movable membrane (6) having a surface (6b) operably exposed to pressure from the inlet (5) and the casing (2) comprises a first substantially glass-shaped curved coil body (3) having a tubular foot (3a). ) in which the inlet (5) is defined, a mouth (3e) located on the opposite side, and a second body (4) in the form of a tubular coil, fixed on the first body (3) and having a first portion end (4a) which encloses a peripheral portion (6a) of the membrane (6), an intermediate axial portion (4b) around which is wound said coil (9) and a second end portion (4c) which defines a reaction surface (4e) against which a spring (16) associated with a u mobile (13).

Description

More particularly, the present invention relates to an inductive sensor

  hydraulic pressure apparatus, particularly for domestic appliances, boilers and the like, of a type comprising a rigid casing having at least one (first) inlet for a hydraulic pressure to be measured, and in

  which is defined a chamber in which is mounted, in a liquid-tight manner, a movable membrane having a surface operably exposed to hydraulic pressure from the inlet; to the membrane is connected a movable ferromagnetic core, under the effect of said pressure with respect to a stationary coil supported by said envelope, against the reaction of first elastic means, so that during operation, the inductance of said coil varies depending on the value of said hydraulic pressure.

  The object of the present invention is to provide an inductive pressure sensor of the above-mentioned type, which has improved characteristics, both as regards the insulation with respect to water of its electrical parts and the simplification of its structure. and its assembly.

  These objectives as well as other objectives are achieved according to the invention with an inductive pressure sensor of the aforementioned type, characterized in that the envelope comprises: a first body, substantially bent in the form of a glass, having a tubular foot in which said inlet is defined, and a mouth located on the opposite side to said tubular foot, and a second tubular coil-shaped body, fixed to the first body and having a first end portion which sealingly encloses a liquid, a peripheral portion of said membrane, an intermediate axial portion around which is wound said coil; and a second end portion which defines a reaction surface against which said elastic means associated with the movable core react; the arrangement being: such that the core is movably mounted within said second body, between the membrane and said resilient means of reaction.

  Other features and advantages of the present invention will be mentioned in the detailed description which follows, carried out simply by way of non-limiting example, with reference to the attached figures, which show: FIG. 1: a front view of a first inductive sensor pressure device according to the present invention; 2 is an exploded perspective view showing the inductive pressure sensor 1.5 according to FIG. 1; 3: a sectional view along line III-III of FIG. 1, FIG. 4: a sectional view along line IV-IV of FIG. 3, FIG. 5: a side view of a body in the form of a coil included in the sensor according to the preceding figures, Figure 6: a sectional view along the line VI-VI of Figure 3, Figures 7 and 8: sectional views similar to that of Figure 4, which show two alternative embodiments. of the sensor device according to the present invention, and Figure 9: a sectional view showing another alternative embodiment of the device according to the present invention.

  In the figures, the reference numeral 1 generally designates an inductive hydraulic pressure sensor according to the present invention.

  The sensor 1 comprises a rigid envelope, generally designated 2, consisting of a first body 3, bent slightly in the form of glass, and a second body 4 substantially in the form of a tubular coil.

  The glass-shaped body 3 has, at its lower part, a tubular foot 3a in which is defined a connection or inlet duct 5 (Figures 3 and 4) for a hydraulic pressure to be measured.

  In the embodiment shown by way of example, next to the tubular foot 3a, the glass-shaped body 3 has a first portion 3b having an increased diameter, then an intermediate portion 3c having a further increased diameter, and finally a upper end portion 3d having a further increased diameter.

  The tubular coil-shaped body 4 has a lower end portion 4a whose end edge presses, in a liquid-tight manner, against the glass-shaped body 3, by the peripheral portion 6a of a membrane generally. This membrane has a surface 6b operably exposed to the hydraulic pressure from the inlet fitting or conduit 5 (FIGS. 3 and 4).

  The coil-shaped body 4 has an intermediate axial portion 4b which has an outer annular flange 7, which supports an annular hydraulic sealing member 18, (preferably on the membrane-facing portion 6, i.e. say towards the inlet connection 5), against the glass-shaped body 3.

  The coil-shaped body 4 has a second end portion 4c, having an end portion 4d which encloses the upper mouth 3 of the glass-like body 3 and which defines a second external annular flange 8 substantially parallel to the flange 7 .

  Between the flanges 7 and 8, around the intermediate portions 4b of the coil-shaped body 4, is wound a coil 9.

  The fixing of the coil-shaped body 4 to the glass-like body 3 is carried out by means of ratchet ribs 10 (FIGS. 3 and 4), made in the lower axial portion 4a of said body and which fit into each other. openings or corresponding housings 11, predisposed in the portion 3b of the glass-shaped body 3.

  In the rigid envelope of the sensor, between the upper end of the foot 3a of the glass-shaped body and inside the end portions 4a and 4b of the spool-shaped body 4, is defined a generally designated chamber. by reference numeral 12. In said chamber extends a movable ferromagnetic core 13 connected to the membrane 6. In the embodiment shown by way of example, the core 13 comprises a ring 14 made of a ferromagnetic material, entirely encapsulated in an envelope 15 made of an electrically insulating material, for example molded plastics material.

  A coil spring 16 bears down against the upper end of the core 13 and up against a reaction surface 4e defined in the upper end portion 4c of the coil body 4.

  In operation, the core 13 moves relative to the stationary coil 9, under the effect of the pressure exerted on the connection or the inlet duct 5, so that the inductance of the coil 9 varies. according to said pressure.

  The coil 9 is connected in a manner not shown to an elaboration circuit, comprising, for example, a capacitor whose capacitance constitutes, thanks to the inductance of said coil 9, an LC circuit resonant at a variable frequency depending on the inductance of the coil 9 and therefore the pressure at the input 5 of the sensor.

  Said elaboration circuit may be suitably supported by a printed circuit board 30 (FIGS. 2-6) which, in the embodiment shown, is substantially U-shaped (FIG. 2) and is inserted between the upper portion 4d and the flange 8 of the body 4, around the portion 4c of the latter. One end 30a of the plate 30 has conductive connecting tracks and is coupled to a connector 31 (FIGS. 2 and 3) which is wedged between the coil-shaped body 4 and the glass-like body 3.

  The sensor according to the invention, described above, has many advantages.

  In the first place, its supporting structure or envelope 2 consists solely of two bodies, that is to say the glass-shaped body 3 and the body-shaped coil 4, which can easily be coupled together.

  Another advantageous characteristic is represented by the double electrical insulation of the coil 9 with respect to the hydraulic fluid (water) introduced at the inlet connector 5. The double insulation is guaranteed on the one hand by the peripheral portion 6a of the membrane 6, inserted in a sealed manner between the bodies 3 and 4, and on the other hand by the sealed annular member 18 inserted between the body 3 and the flange 7 of the coil-shaped body 4.

  Another protection is constituted by the integral encapsulation of the ferromagnetic core 4 in the electrically insulating casing 15.

  FIG. 7 shows a pressure sensor according to the invention which has some modifications with respect to the embodiment described above with reference to FIGS. 1-6.

  In FIG. 7, the parts and elements already described have been assigned again the same references as those used previously.

  A first difference of the device according to FIG. 7 is that, in the portion of the upper end 4c of the coil-shaped body 4, a second inlet connection 19 is formed by means of which a second pressure can be injected into the portion of the chamber 12 which is situated on the opposite side to the first inlet connector 5 with respect to the membrane 6.

  By virtue of said characteristic, the sensor device according to FIG. 7 is of the differential type, and during operation, the axial position of the core 13 with respect to the coil 9 depends on the difference between the pressures applied to the inlet connections 5 and 19. Correspondingly, the inductance of the coil 9 also depends on said pressure difference.

  A second difference presented by the device according to FIG. 7 is the addition of an additional helical spring 17 which rests, at its lower part, against a shoulder predisposed on the tubular foot 3a of the glass-shaped body 3 , and at its upper part, against the membrane 6.

  The spring 17 acts on the membrane 6 and on the associated core 13 in the opposite direction to the action exerted on them by the spring 16.

  The addition of the spring 17 is not necessarily related to the realization of the pressure sensor device of the differential type, as in the figure, this spring possibly being added also in a sensor made with a single pressure inlet, as on Figures 1-6.

  FIG. 8 shows a further variant embodiment of a pressure sensor according to the present invention. In this figure also, to the parts and elements already described, were again assigned the same references.

  The sensor according to FIG. 8 is intended more particularly for use in a boiler for domestic heating, for example a wall-mounted boiler. When said boiler is installed on the construction site of a building or the like, the installer may wonder if, at the inlet connection 5 of the pressure sensor, there is a fluid under pressure, and this before the sensor is electrically powered and can provide its own signal. In order to enable the installer to know under such conditions whether the inlet connection 5 of the pressure sensor is under pressure, on the variant according to FIG. 3, the inlet connection 5 communicates with a duct 20 which extends to least 2882434 to the outside of the sensor shell 2, and is preferably at least partially transparent. In the duct 20 is mounted a movable body, such as a small ball 21, for example of red color, susceptible, when is applied, at the inlet connector 5, a hydraulic pressure, to take a position (such it is represented in a continuous line in FIG. 8) in which it is visible from the outside and indicates the presence of pressure at the inlet connection 5.

  When the pressure decreases at the inlet connection 5, the body 21 I0 descends under the effect of gravity, by placing itself in the rest position, as shown in dashed lines in FIG. 8, resting on elements provided in the conduit 20.

  The above variant, described with reference to FIG. 8, may optionally be implemented in a differential sensor of the type shown in FIG. 7, with or without the additional spring 17.

  In the variant shown in FIG. 9, to the parts and to the elements already described, the marks previously used have been allocated again.

  This variant differs from the previous ones essentially with regard to the following aspects.

  The glass-shaped body 3 still has a staggered profile, but has a reduced number of axial portions: in FIGS. 3 and 7, the portion indicated by the reference 3d is missing, whereas the portion 3c is longer, and its vertex defines the mouth 3 of the body 3. Said mouth 3 is not enclosed by an upper portion of the coil-shaped body 4, but by a separate cover 50 and coupled, for example by means of a snap, with the portion of the top of the body 3.

  In the variant according to FIG. 9, the central portion of the membrane body 6 is greatly enlarged. As in the variant shown in FIG. 7, between said membrane body 6 and the lower portion 3a of the body 3 is suitably arranged a spring 17.

  The core 13 is furthermore made in a simplified manner.

  In the variant according to FIG. 9, may also be added a device for signaling the presence of pressure, such as that indicated by the marks 20 and 21 of FIG. 8.

  Of course, while maintaining the principle of the invention, the modes and details of implementation may be greatly modified with respect to what has been described and shown above by way of non-limiting example, the present invention s extending to all embodiments that aim for the same utility through the same innovative concepts.

2882434 10

Claims (12)

  An inductive hydraulic pressure sensor (1), more particularly for domestic appliances, boilers and the like, comprising a rigid casing (2) having at least a first inlet (5) for a hydraulic pressure to be measured, and in which is defined a chamber (12) in which a movable diaphragm (6) having a surface (6b) operatively exposed to the hydraulic pressure from said inlet (5), a ferromagnetic core, is mounted in liquid-tight manner; (13) mobile connected to said membrane, under the effect of said pressure, with respect to a stationary coil (9) supported by said casing (2) against the action of elastic reaction means (16), so during operation the inductance of said coil (9) varies as a function of the value of said hydraulic pressure, characterized in that the casing (2) comprises a first body (3) curved substantially in the form of glass, with a tubular foot (3a) in which said inlet (5) is defined, and with a mouth (3e) located on the opposite side to said tubular foot (3a), and a second body (4), in the form of a tubular coil, attached to the first body (3) and having a first end portion (4a) which sealingly encloses with a hydraulic seal a peripheral portion (6a) of said membrane (6), an axial portion intermediate (4b) around which is wound said coil (9), and a second end portion (4c) which defines a reaction surface (4e) against which support said elastic means (16) associated with the movable core (13); the arrangement being such that the core (13) is movably mounted within said second body (4), between the membrane (6) and said elastic means (16).   2. Pressure sensor according to claim 1, characterized in that the intermediate portion (4b) of the coil body (4) encloses, on the side facing the membrane (6), with respect to said first body (3), an element hydraulic sealing (18).   3. Pressure sensor according to claim 1, characterized in that said first end portion (4a) of the coil body (4) has snap-in anchoring means (10) engaged in corresponding retaining housings (11). ) of the first body (3).   4. Pressure sensor according to claim 3, characterized in that said anchoring means (10) are located between the membrane (6) and said annular sealing member (18).   5. Pressure sensor according to one of the preceding claims, characterized in that the core (13) has a tubular element (14) consisting of a ferromagnetic material, encapsulated in an electrically insulating casing (15).   Pressure sensor according to one of the preceding claims, characterized in that additional resilient means (17) acting on the side (6b) of the diaphragm (6) is operationally exposed to said pressure. hydraulic to measure, and urge it in the opposite direction to the action exerted by said first elastic means (16), are associated with the membrane (6).   2882434 12 7. Pressure sensor according to one of the preceding claims, characterized in that, in said second end portion (4c) of the coil body (4), a second inlet (18) is formed for a second pressure to be measured. said second inlet (19) communicating with a portion of said chamber (12) which is situated on the opposite side to the first inlet (5) with respect to the membrane (6), the arrangement being such that, during operation, the position of the core (13) with respect to the coil (9) depends on the difference between the pressures applied to said first and second inputs (5, 18).   8. Pressure sensor according to one of the preceding claims, more particularly for use in domestic heating boilers, characterized in that at least a first inlet (5) is in communication with: a conduit (20) in which is mounted a movable body (21) capable, when a pressure is applied at said first inlet (5), to take a position in which it is visible from outside the envelope (2) and signals the presence of a pressure at said first input.   9. Pressure sensor according to one of the preceding claims, characterized in that said coil (9) is connected to a processing circuit supported at least in part by a connection plate (30) connected to said coil body (4). ).   A pressure sensor according to claim 9, characterized in that said connecting plate (30) is substantially U-shaped, and is disposed around a portion (4c) of the coil body (4).   2882434 13 11. Hydraulic pressure sensor according to one of the preceding claims, characterized in that said second end portion (4c) of said second body (4) encloses the mouth (3e) of the first body (3).   12. Pressure sensor according to one of claims 1 to 10, characterized in that at the mouth (3e) of said first body (3) is associated a closure cap (50).